Cam action coaxial switch



Nov. 26, 1957 F. E. cocKERHAM K 2,814,696

CAM ACTION COAXIAL SWITCH Filed July 29, 1955 m Illa United States Pateirfv O a 2,814,696 CAM ACTION COAXIAL SWITCH Frank E. Cockerham, Bay Village, Chio, assignor to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application July 29, 1955, Serial No. 525,131

6 Claims. (Cl. 20G-453;)l

The present invention relates to improvements in coaxial switches and is, more particularly, concerned with the provision of simplified and electrically improved means for assuring electrical continuity in coaxial switches.

As those skilled in the art of coaxial switch construction are aware, the over-all eiciency of coaxial switches when utilized for the distribution of high frequency electrical signals, such as encountered in radio, radar and television operation, depends upon the eicient connection of the movable rotor conductor with a plurality of conductors xedly positioned in the switch housing. In the past, several techniques 'of minimizing losses in the transfer of electrical signals from housing to rotor andrvice versa have been made. Among such attempts may be found structures providing peripherally flanged rotors cooperating with radially split side conductors, attempts to manufacture the switch rotor-to-housing clearances at an absolute minimum, and other similarly expensive methods. In contrast to such prior art constructions, the present invention contemplates the provision of an ex# tremely simple switch requiring only conventional ma# chining tolerances and operating to provide a constantly snug, electrically eiiicient, interconnection between diverse coaxial conductors.

In accordance with the principles of the present invention, a `coaxial switch housing is provided in which a rotor is eccentrically mounted in such a manner that only a portion of the rotor periphery is in juxtaposition with the inner surface of the housing. The portion of the switch rotor located between the portions thus in juxtaposition with the housing and which carries an electrical distribution conductor is separated from the portion of the rotor positioned substantially out of contact .with the housing by a ramp or ycam surface. Each of the. side conductors is provided with a spring biased contact finger which, under the inllue'nce of the spring, is urged inwardly against the rotor. Stops are Yprovided for the fingers to prevent their passage into ythe rotor'cavity beyond a predetermined amount such that the fingers do not contact the rotor surface except immediately prior t-o and during switching contact between the rotor conductorand respective side conductors. As therotor is turned in switching operation, successive side conductor fingers `engage the ramp and are forced outwardly against the nger spring. This provides a positive wiping `action as the finger slides onto the end of the rotor conductor and, further, assur a snug, electrically eicient, contact between the rotor conductor `and the individual side conductors.

Accordingly, it is an object of the present invention to provide `an improved coaxial switch in whi'chidle side conductors are open-circuite-d and the side vconductor or conductors in use are positively spring biased into firm engagement with the rotor conductor.

A further object of Vthe present invention is to provide 2,814,696 ,Ptsntd se 26 19,5"

ICC

2, a simplified coaxial switch rotor and housing assembly having improved electrical eiciency.

Yet a further object of the present invention is to provide va multiple throw coaxial switch having superior electrical continuity while isolating inactive conductors without use of costly dielectric inserts in the rotor.

A feature of the invention resides in the use of `at least one cam surface on the rotor for controlling a spring pressed side conductor.

Still -other and further objects land features of the present invention will at once become apparent to those skilled in the art from 'a considerationrof the attached drawings wherein one preferred lembodiment of the invention is shown by way of illustration only, and wherein: I I

Figure l is a side elevational view in cross-section of a coaxial switch incorporating a structure in accordance with the present invention; and

Figure 2 is a cross-sectional view taken along the line II-II of Figure 1.

As shown on the drawings:

In the embodiment illustrated7 a single pole double throw coaxial switch having a housing 10, rotor 11 and ratchet detent means 12 is shown. The housing 10 is generally conventional in construction and comprises a plurality 'of branch 'or side terminal supports 14, 15 and 1,6. The terminals carry, respectively, dielectric plugs 17, 18 and 19 in which tubular connectors Ztl, 21 `and 22 are positioned, preferably during the molding of the dielectric members. The respective tubular connectors are provided with connector conta-cts 23, 24 and 25 resiliently urged uradially inwardly toward the rotor 11 by springs 26, 27 and 28. The respective 'contacts are prevented from radially inwardly directed travel beyond a predetermined point illustrated by the position of the contacter 25 by means of spun over stop lips 29, 30 and 31, respectively. n As may be seen, the rotor 11 is segmental cylindrical throughout a peripheral length indicated yby the arc 32, 33, 34, viewed in Figure 2. Within this segmental cylindrical portion, a rotor conductor 35 is rigidly mounted in a tubular dielectric member 36 such that the ends 35a and 35h thereof are positionedon the periphery of the segmental cylindrical portion of the rotor. As shown, the rotor conductor 35 lies in a plane substantially perpen* dicular to the axis of rotation of the rotor.

The remaining peripheral portion of the rotor 11, comprising the arcuate portion 34, 37, 38, 32 is 'formed by an `arc having a radius of curvature somewhat larger than the radius ofcurvature of the segmental cylindrical portion 32, 33, 34 and preferably merges therewith at the points 32 and 34 in a smoothly rounded manner.

In View 4of its non-circular nature, the rotor 11 is preferably mounted as shown in Figure l by its driveshaft 11a and a stub shaft 11b supported in bushings lha and 10b respectively positioned in the housing 1t) and the housing cap 10c. Clearance chamfers llc` and 11d are provided to `accommodate any dust or other foreign particles which might otherwise clog `the switch and cause binding or erratic operation.

As a result of the construction above set forth, it will be apparent that rotation of the rotor 11 in a clockwise direction as viewed in Figure 2 will cause the rotor c011- ductor 35 to shift from a position connecting contacts 23 and 24 to a position connecting contacts 24 and 25. In this switching operation, the spring pressed contact 25 will be initially moved radially outwardly relative to i tact 25 will be heavily spring biased as it passes acrossl and into position on the rotor conductor 35, thereby as suring a clean, tight electrical connection.

Simultaneously with the switching operation above described, the contact 23 will slide down the ramp portion 32, 3S into a free position similar to that shown at the contact Z in Figure 2, in which the contact 23 is electrically isolated from the rotor l1 as well as from the housing itl. Thus, in the inactive or idle position each of the contacts 23, 2d or 2S is electrically disassociated from all remaining switching elements by the volume of air dielectric in the chamber di). At the same time, through the provision of the cam surfaces, a positive contact is assured.

It will be apparent to those skilled in the art that the area of the segment bounded by the peripheral arc between the points 37, 38 and a chord drawn between these points, may be eliminated without affecting the operation of the switch. Such elimination would, of course, provide a greater volume of air dielectric and the saving in weight would, in certain applications, prove desirable. Further, it will be understood that the rate of cam inclination of the surface 34, 37, or 32, 33 may vary as desired. The spring tension applied to the contacts 23, 2d, may be increased without changing the spring biasing each of these contacts by providing a longer contact and a sharper or more abrupt incline to the surface sl, 37 or alternatively, in the case where the area of the segment above mentioned is free of rotor material, by extension of the ramp to some further point such as for example 37a.

While in the embodiment illustrated, a coaxial switch of the type in which side conductors are controlled is shown, nevertheless it will be understood that the cam feature of the present invention may be used with rotors in which a central, axial, conductor distributes an electrical signal to one of a group of side conductors. In such an arrangement, the single conductor outlet at the periphery of the rotor it) would be preceded, in the direction of rotation, by a cut away cam ramp identical to that shown at 3d, 37 in the drawings. In such a construction, the central, axially directed conductor would preferably be coaxial with the axis of rotation of the rotor and have a contactor in association with the end of a rotor conductor carried by the stub shaft 1lb and extending through the stub shaft and radially outwardly to the periphery of the rotor.

It will, of course, be further apparent to those skilled in the art that additional variations and modifications may be made in accordance with the principles of the present invention without departing from the scope of the novel concepts hereinabove set forth. Accordingly, it is my intention that the scope of the present invention be limited solely by that of the hereinafter appended claims.

I claim as my invention:

l. A coaxial switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor and electrically isolated therefrom by dielectric mounting means, said rotor having a limited portion of its periphery of substantially the same diameter as said bore and the remainder of its periphery removed from the inner surface of said housing which defines said bore, at least one contact carried by said housing in electrically isolated relation thereto and projecting into said bore, biasing means urging said one contact toward said rotor and into a position extending into said bore, at least one end of said rotor conductor being positioned at the said limited portion of the periphery of said rotor for face to face contact with said one Contact, and cam means on said rotor for urging said one contact outwardly against said biasing means prior to positioning of said rotor and rotor conductor and said one contact in face to face relationship upon rotation of said rotor.

2. A rotary switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor and electrically isolated therefrom by dielectric mounting means, said rotor having a limited portion of its periphery of substantially the same diameter as said bore and the remainder of its periphery removed from the inner surface of said housing defining said bore, at least one Contact carried by said housing in electrically isolated relation thereto and projecting into said bore, biasing means urging said one contact toward said rotor into a position projecting into said bore, at least one end of said rotor conductor being positioned at the said limited portion of the periphery for contact with said one contact and an inclined ramp connecting said limited portion of the periphery of said rotor with the remainder or said periphery, said ramp acting as a cam during rotation of said rotor for moving said contact outwardly against said biasing means immediately prior to positioning said rotor conductor in contact with said one Contact.

3. A rotary switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor and electrically isolated therefrom by dielectric mounting means, means positioning one end of said conductor immediately adjacent the cylindrical surface of said bore, at least one contact carried by said housing in electrically isolated relation thereto and projecting into said bore, biasing means urging said one contact toward said rotor and into a position extending into said bore and cam means carried by said rotor adjacent said one end of said rotor conductor for contacting said one contact and forcing said one contact outwardly against said biasing means immediately prior to contact between said one end of said rotor conductor and said one contact.

4. A rotary switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor and electrically isolated therefrom by dielectric mounting means, said rotor having a limited portion of its periphery of substantially the same diameter as said bore and the remainder of its periphery removed from the inner surface of said housing deiining said bore, `at least one contact carried by said housing in electrically isolated relation thereto and projecting into said bore, at least one end of said rotor conductor being positioned at the same limited portion of the periphery for face to face contact with said one contact, biasing means urging said one contact toward said rotor and into a position extending into said bore a distance less than the distance by which the said remainder of the rotor periphery is removed from the inner surface of the housing, and cam means on said rotor adjacent said one end of said rotor conductor for moving said one contact outwardly against said biasing means for wiping contact with said one end of said rotor conductor upon rotation of said rotor.

5. A high frequency coaxial switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor electrically isolated therefrom by dielectric mounting means, said rotor having a limited portion of its periphery of substantially the s'ame diameter as said bore and the remainder of its periphery removed from the inner surface of said housing defining said bore, means positioning both ends of said conductor at angularly spaced points on said limited portion, a plurality of contacts carried by said housing in electrically isolated relation thereto and projecting into said bore, biasing means urging said contacts toward said rotor into a position extending into said bore Iand an inclined cam surface on said ro-tor immediately adjacent at least one end of said roto-r conductor on the portion facing direction of rotor rotation and connecting said limited portion of said rotor periphery to the remainder of said rotor periphery whereby rotation of said rotor will force each of said contacts outwardly against said biasing means immediately prior to electrical contact between said rotor conductor and said outwardly urged contact.

6. A high frequency coaxial switch comprising a housing having a cylindrical bore therein, a rotor mounted for rotation in said cylindrical bore, a conductor carried by said rotor electrically isolated therefrom by dielectric mounting means, said rotor having a limited portion of its periphery of substantially the same diameter as said bore and the remainder of its periphery removed from the inner surface of said housing delining said bore, means positioning both ends of said conductor at angularly spaced points on said limited portion, a plurality of contacts carried by said housing in electrically isolated rela- 6 v tion thereto and projecting generally radially into said bore, biasing means urging said contacts toward said rotor and into a free position extending into said bore a distance less than the distance by which said remainder of said rotor periphery is removed from the inner surface of said housing bore.

Charles June l2, 1951 Sawyer et al. Mar. 1, 1955 

